a. Field of the Invention
The present invention generally pertains to marine propulsion device protection while a marine propulsion device is in operation, and more particularly to protection of a skeg, a propeller and a lower unit of an inboard/outboard motor in operation while improving the performance of an inboard/outboard motor.
b. Description of the Background
When an inboard/outboard motor is in operation, its lower unit component parts can easily be damaged by rocks, debris and other objects. Because such damage is expensive to repair, devices have been developed to protect the lower unit components of an inboard/outboard motor from damage. In particular, the skeg, the propeller and the lower unit of an inboard/outboard motor may each be protected from common forms of damage by devices well-known in the prior art.
Devices in the prior art that protect the skeg and propeller of an inboard/outboard motor from damage include a skeg enclosure, which tightly encloses part or all of the large flat sides of a skeg to protect it from damage. Such enclosures are commonly “one-size-fits-all” devices to protect most common skeg sizes and shapes. U.S. Pat. No. 5,018,997 (Guptill), which is specifically incorporated herein by reference for all that it discloses and teaches, discloses such a skeg enclosure made of stainless steel. However, Guptill does not teach any method of combining a skeg enclosure with any other device.
A common form of protection for both propellers and lower units utilizes a plate that is mounted near the propeller or lower unit to act as a debris deflector. The plate, in addition to deflecting debris from the propeller or lower unit, is also designed to absorb the force of any collision with rock or debris. If the force is large enough, the plate undergoes deformation itself to prevent deformation of the propeller or lower unit. The plate typically creates a drag on an inboard/outboard motor, reducing the efficiency of the inboard/outboard motor. Propeller protectors and lower-unit protectors in the prior art typically protect smaller inboard/outboard motors up to about 50 horsepower.
Other devices in the prior art for protecting an inboard/outboard motor include an elongated rigid bar that deflects debris and protects a skeg from damage, as well as a lower-unit protector that protects the lower unit of an inboard/outboard motor by deflecting some debris and absorbing damage from other debris. U.S. Pat. No. 6,503,110 (Lammli), which is specifically incorporated herein by reference for all that it discloses and teaches, discloses a lower-unit protector that uses fasteners to attach to a lower unit of an inboard/outboard motor. Lammli teaches that a rigid bar, which deflects debris and absorbs collision damage, may be combined with a reinforcement member to better absorb or deflect debris. Lammli further teaches the use of fasteners to attach a lower-unit protector to an inboard/outboard motor but does not teach a method of attaching a lower-unit protector to an inboard/outboard motor without fasteners. Lammli also does not teach any method of combining a lower-unit protector and a skeg enclosure into a single device.
One drawback of inboard/outboard motor protection devices is that use of such devices typically reduces the speed and efficiency of a boat and adversely affects the quality of the ride. One method of counteracting the effects of such devices is a hydrofoil, commonly attached above the lower unit and riding at the surface of the water during operation. A hydrofoil typically raises the inboard/outboard motor out of the water, which keeps the motor on an even plane, reduces drag on the boat from the surrounding water, improves the speed of the boat and allows the motor to move the boat faster while using less fuel. Hydrofoils in the prior art are designed in various shapes and are separate from motor protection devices. U.S. Pat. No. 6,095,875 (Allison), which is specifically incorporated herein by reference for all that it discloses and teaches, discloses a hydrofoil containing a plate that has plate tips downturned at a dihedral angle of between about 25° and about 45° with respect to the plate. However, Allison does not teach any method of combining a hydrofoil with a debris-protection device, nor does it teach that a hydrofoil can operate underwater.
Devices that protect a skeg, a propeller or a lower unit commonly protect only one or two of those three. Thus, simultaneous use of more than one device is typically required to protect a skeg, a propeller and a lower unit. Protection of a single inboard/outboard motor and counteracting the adverse effects of such protection may require both multiple inboard/outboard motor protection devices and a hydrofoil.
It would be advantageous to create a single inboard/outboard motor protector device for larger inboard/outboard motors (up to about 250 horsepower) that combines the functions of skeg protection, propeller protection and lower unit protection while minimizing the resulting drag. It would further be advantageous if such an inboard/outboard motor protector also contained a hydrofoil that operates underwater to improve the efficiency of an inboard/outboard motor and improve the speed and riding quality of a boat using an inboard/outboard motor.